1. Field of the Invention
This invention relates to a method for fabricating a resist pattern, a method for patterning a thin film and a method for manufacturing a micro device.
2. Related Art Statement
Thin film-patterning is performed by using a milling method, a lift-off method or a combination method of milling and lift-off. Then, a resist pattern for the thin film-patterning is normally formed in a T-shaped cross section or a reversed trapezoid cross section, for repressing the burr from the removed material attached to the side surfaces of the resist pattern and facilitating the removal of the remaining material.
Normal exposure treatment and development treatment carried out as shown in Japanese Examined Patent publication Kokoku Hei 7-6058(JP B 7-6058), such a resist pattern is constructed of a two-layered structure, that is, a Bi-layered type resist pattern, which includes a photoresist layer as a top layer and a polymethylglutarimide layer as a bottom layer.
Moreover, the resist pattern can be fabricated as described in Japanese Patent No. 2922855. In this case, a negative working agent is added to a positive photoresist containing an alkaline soluble phenol resin and naphthoquinonediazido to prepare a photoresist material having picture inversion function. Then, the photoresist material is exposed and developed, and subsequently, heated to fabricate the resist pattern.
Furthermore, the resist pattern can be fabricated as follows: First of all, a phenol dissolution accelerator is added to a novolac type positive photoresist to prepare a so-called MG type photoresist material. Then, the MG type photoresist material is exposed and developed to fabricate the resist pattern.
However, a minute resist pattern can not be fabricated due to the optically theoretical limitation of a illumination beam to be used in the exposed process. Accordingly, only a wider resist pattern can be fabricated, and thus, only a wider thin film pattern can be fabricated.
Moreover, in the above-mentioned T-shaped or reversed trapezoid resist pattern, the lower portion is set to be narrower than the main body to define the patterning width. Therefore, the contact area between the resist pattern and a base material is narrower, compared with the total size of the resist pattern, in some case, resulting in the degradation of the adhesive strength of the resist pattern to the base material.
Accordingly, in the case that the thin film-patterning is carried out using such a resist pattern, the resist pattern is broken away at the development process, and thus, precise thin film-patterning can not be carried out.